Perpendicular magnetic recording: Writing process

Abstract

Recording, noise, and medium microstructure in perpendicular recording with a soft magnetic underlayerIn this article, a detailed overview of the methodology to design a write transducer for recording onto perpendicular media at areal densities beyond 1 Tbit/in. 2 is presented. The two basic modes of perpendicular recording, single-layer recording media in combination with a ring type head and double-layer recording media with a soft underlayer in combination with a single pole head, are compared with each other theoretically and experimentally. Moreover, perpendicular recording is compared to longitudinal recording from the perspective of the writing process. The system efficiency is redefined for perpendicular recording to take into account the critical role of the soft underlayer. The effects of using ''soft'' magnetic shields around the trailing pole are analyzed. It is shown that at least a factor of 2 increase in the field can be obtained at areal densities beyond 500 Gbit/in. 2 if shields are used. Such an open issue as the skew angle sensitivity in perpendicular recording is analyzed. It is shown that using soft magnetic shields around the trailing pole substantially improves the skew angle sensitivity. Moreover, using shields substantially improves the system efficiency and to some degree fulfills the role of the soft underlayer in perpendicular recording.

Spin dynamics and frequency dependence of magnetic damping study in soft ferromagnetic FeTaC film with a stripe domain structure

“…The polar angle variation of resonance field and linewidth at different frequencies have been analyzed numerically using Landau-Lifshitz-Gilbert equation by taking into account the total free energy density of the film. The numerically estimated parameters Landé g-factor, PMA constant, and effective magnetization are found to be 2.1, 2×10 5 erg/cm 3 and 7145 Oe, respectively. The frequency dependence of Gilbert damping parameter (α) is evaluated by considering both intrinsic and extrinsic effects into the total linewidth analysis.…”

“…The current researchers are more keen to focus on STT technology for its high density magnetic random access memories (MRAM), 2,3 STT-driven domain wall devices 4 and perpendicular magnetic recording media 5 applications. In order to make this technology more efficient, lowering the critical current density is essential which requires the material specifications with low saturation magnetization (M S ), high spin polarization, large uniaxial perpendicular magnetic anisotropy (PMA) constant and low magnetic damping.…”

Critical Parameters of Solution Design for Electrodeposition of 2.4 T CoFe Alloys

“…The most insoluble metal hydroxide when Co and Fe are considered is Fe(OH) 3 with the product of solubility, K p = 2. [1] Here, K w is the ionic product of water, and K p is defined previously. If the net flux of hydrogen ions towards the electrode surface through the diffusion layer during the galvanostatic deposition is expressed in terms of current density j and current efficiency γ as; j(1-γ)/F, then the concentration of the hydrogen ions at the electrode/solution interface, …”

Three-Dimensional Magnetic Recording Device

“…The variation of biasing is produced by a relatively small electric current (-100 mA turn) through a wire underneath the SUL. This method was developed by PI during the development of perpendicular magnetic recording at Seagate Research [27]. A schematic diagram showing the mechanism of biasing the SUL is shown in Figure 13a.…”

“…In this mode, the SUL is necessary to increase the recording field throughout the entire thickness of the recording medium [8]. Previously, it was shown that the increase by at least a factor of two is feasible [9]. Typically, the magnetic "image" model ['0, "] is used to illustrate the increase of the recording field due to the SUL.…”